Wang's spokesman Ringo Wong said Wang died Tuesday. He did not describe the cause of death, but Hong Kong media reported that Wang had ovarian cancer that spread to her liver and other organs.
Wang's rise to become Asia's richest woman, according to Forbes Asia, had the plot elements of a Hollywood movie — sex, romance, crime and courtroom drama.
Born Kung Yu-sam in Shanghai, Wang moved to Hong Kong in the 1950s with Teddy Wang, who founded the Chinachem Group pharmaceutical company.
Teddy Wang was abducted in 1990 as he left Hong Kong's exclusive Jockey Club. The family paid a $33 million ransom but he was never returned.
Several of the kidnappers were caught and said that the 56-year-old Wang had been thrown into the sea from the sampan — a small Chinese boat — where he was held.
His body was never found and he was declared dead in 1999.
Nina Wang insisted that she believed Teddy Wang was alive and would someday return. He had been kidnapped seven years earlier and released for $11 million ransom.
In her husband's absence, Nina Wang built Chinachem into a massive private property developer, with office towers and apartment complexes throughout Hong Kong.
Forbes magazine ranked her this year as the world's No. 204 richest person, with a fortune of $4.2 billion.
Wang captivated the public with her pigtails and garish, girlish outfits. She was nicknamed "Little Sweetie," the Chinese name of a princess-like character from a Japanese fairy-tale cartoon.
But Wang's standing came under threat when her father-in-law, Wang Din-shin, challenged her claim to his late son's fortune.
Wang Din-shin, who is in his 90s, said he was the sole beneficiary of Teddy Wang's estate, based on a 1968 will.
He questioned a will dated a month before his son disappeared, which left everything to Nina Wang. All four documents in the will contained the handwritten message, "one life, one love," in English on papers that were otherwise in Chinese.
After a 171-day trial during which Wang Din-shin showed pictures of Nina Wang with an alleged lover, a Hong Kong judge ruled in November 2002 that Nina Wang's will was fake and she "probably" forged part of it.
The love messages seemed suspiciously out of place, the judge said.
Prosecutors charged her with forgery in January 2005 in a separate criminal case. She was released on $7 million bail, a record for Hong Kong at the time.
Nina Wang, however, staged a legal comeback.
Hong Kong's Court of Final Appeal reversed the ruling giving the estate to her father-in-law, saying the signatures on the will appeared authentic.
"Such naturalness and style of writing is inconsistent with that of a person trying to commit a forgery," Judge Patrick Chan said.
Wang was also cleared of forgery charges in December 2005.
Martin Lee, a prominent lawyer and lawmaker, recalled Nina Wang as a careful spender and described Nina and Teddy Wang as a genuinely loving couple.
"They didn't just go on vacation together, work together. I believe they spent every day together," Lee told reporters.